Elektra Maxi - PID and safety switch

Equipment doesn't work? Troubleshooting? If you're handy, members can help.
jyl

Postby jyl » Feb 10, 2019, 4:30 pm

I have Elektra #1 installed and running in the dining room.

Question 1: I'm starting to seriously think about installing a PID for three reasons.

1. The Sirai pstat is kind of noisy when it clicks on and off. This is a minor point but bothersome nonetheless.

2. I'm nervous about having only one device preventing an overpressure and potentially water leak into my dining room. In theory the catch cup and drain line for the OPV should prevent a mess but I'm not convinced my machine's drain box and 1/2" OD drain line will actually catch everything.

(I've already had a mini flood. That was actually traced to too much drain line extending outside the house which got iced up. But the old drain box, upon inspection, has some cracks that limit its capacity. I switched from 3/8" OD drain line to 1/2" OD line, cut shorter, and a new drain box is on order. For now, I have a drip tray under the machine.)

3. I think it might extend the life of the new and rather pricey Sirai pstat.

So, what would you all recommend for a simple and economical PID setup? What parts, which vendor?

I'm okay with attaching a temperature sensor to the outside of the boiler. I don't feel the need to know the exact temperature inside the boiler and I suspect the difference between outside and inside temp will be fairly consistent.

I would prefer everything be internal to the machine or tucked neatly beneath it (it has tall legs). My wife doesn't want the dining room to look like a laboratory!

Question 2: I'm also thinking about installing the heating element safety switch. I had to replace the old heating element after it shorted, and that was also an expense of I would prefer not to repeat, to say nothing of the flash and pop and tripped breaker. If the water level sensor fails and fries this new element, I could also lose the $100 water heater timer that the machine is wired to.

So, any issue running the safety switch with the PID? I assume the switch is just wired in series with the SSR?
John, Portland OR
Vintage bicycles, Porsche/VW, cooking, old houses.

sar5w

Postby sar5w » Feb 11, 2019, 1:10 am

John
I have put PID controllers on almost all of my single boiler HX machines for most of the same reasons you are thinking. It is quieter, more precise and ends up being cheaper than replacing the p-stat.

I have had good success with the following:

PID - https://tinyurl.com/y59nd366 $25
thermocouple - https://tinyurl.com/y2kok53n $12
SSR - https://tinyurl.com/y6yf5eae $6

The PID can be mounted inside the machine, low away from heat and moisture. The SSR can be mounted to the frame of the machine to help it dissipate heat, close to the element for wiring purposes. I replace the anti-depression valve with the thermocouple because I leave my machines on all the time.

I wire the SSR inline with the p-stat (serving as a switch on one leg going into the p-stat) and set the p-stat to cut power to the element at 1.5 BAR or so. That way if the SSR fails closed, the p-stat will still be there as a backup. I have only had one SSR fail (open).

You might be able to get away with an external temp sensor, but do some testing and see how much the outside of the boiler changes temperature when you steam or introduce cold water into the boiler like when it fills.

The one downside to my setup is that without the anti-depression valve, you tend to get false pressure when the machine is turned off, sits and then is turned back on.

Seth

jyl

Postby jyl » Feb 11, 2019, 9:14 am

Thank you! This looks economical and simple. There is quite a bit of space inside the machine.

I have my machine on a timer so it switches off nightly. Not sure if that's a good idea or not, actually.
John, Portland OR
Vintage bicycles, Porsche/VW, cooking, old houses.

jyl

Postby jyl » Feb 11, 2019, 1:52 pm

I think I'll insert the thermocouple through the vacuum valve fitting, but retain the vacuum valve. Ordered the necessary tee and adapter from McMaster Carr. Now to order a thermocouple. I assume the thermocouple tip should be in the "steam" part of the boiler, not extend into the "water" part, for faster response.
John, Portland OR
Vintage bicycles, Porsche/VW, cooking, old houses.